Weighted device for damping out vibration in an antenna element



June 8, 1965 E. A. SIELAFF 3,188,644

WEIGHTED DEVICE FOR DAMPING OUT VIBRATION IN AN ANTENNA ELEMENT FiledJune 12. 1961 NEUTRAL POSlTl0N T MOTION 0F ELEMENT DEFLECTED INVENTOR.

ERNST A. S/ELAFF A T TORNE YS United States Patent WEIGHTED DEVICE FORDAMPIN G OUT VIBRA- TION IN AN ANTENNA ELEMENT Ernst A. Sielafi, CedarRapids, Iowa, assignor to Collins Radio Company, Cedar Rapids, Iowa, acorporation of Iowa Filed June 12, 1961, Ser. No. 116,376

8 Claims. (Cl. 343-904) This invention relates to an antenna structure,and more particularly to a damping means having a readily flexibleportion and a weighted portion for substantially eliminating vibrationof an antenna element due to external vibration producing forces actingthereon.

As is well known in the art, antenna structures are commonly subject tovarious vibration producing forces, particularly wind forces, that haveheretofore acted to greatly shorten the life of the antenna by causingexcessive vibration of antenna elements, which vibration soon results insnapping or breaking of the elements.

To overcome this problem, many devices have heretofore been proposed orutilized, but none of these devices have been completely successful inproviding a relatively simple, yet dependable damping means that can beused not only on a cantilever antenna element but also on any antennastructure regardless of the manner in which the the present invention.

The damping device of this invention, on the other hand, by utilizingthe structure as described hereinafter, provides a damping means thatcan be used equally well on any type of antenna element subject tovibratory forces regardless 'of the manner in which the antenna elementis mounted.

It is an object of this invention to provide a relatively simple, yetefiicient and reliable means, for damping vibration in any antennaelement the use of which is independent of any particular manner ofmounting of the element.

It is a further object of this invention to provide an antenna structurehaving damping means which may be positioned anywhere along the lengthof an antenna element, which damping means has a readily flexibleportion that extends substantially radially outwardly from the antennaelement and has a weighted portion at its free end which portionscooperate to substantially eliminate vibration in said antenna element.

With these and other objects in view which will become apparent to oneskilled in the art as the description proceeds, this invention residesin the novel construction, combination and arrangement of partssubstantially as hereinafter described and more particularly defined bythe appended claims, it being understood that such changes in theprecise embodiment of the herein disclosed invention may be submitted ascome within the scope of the claims.

The accompanying drawing illustrates one complete example of theembodiment of the invention constructed according to the best mode sofar devised for the practical application of the principles thereof, andin which:

FIGURE 1 is a perspective view of an antenna structure with cantileverantenna elements having damping means thereon as taught by thisinvention;

FIGURE 2 is a perspective view of an antenna structure having antennaelements secured at both ends with damping means thereon spaced fromsaid ends as taught ice by this invention to substantially eliminatevibration in said antenna element;

FIGURE 3 is a side view of the damping means of this invention securedto an antenna element with the damping means shown in section forillustrative purposes;

FIGURE 4 is a cross section view of the damping means of this inventiontaken through the line 44 of FIGURE 1; and

FIGURE 5 is a side view with the damping means shown in sectionillustrating how the damping means absorbs energy to thereby damp outvibrations in an antenna element.

Referring now to the drawings in which like numerals refer .to likecharacters throughout, the numeral 8 refers generally to an antennastructure illustrating the use of the damping means of this invention ona cantilever antenna element, while the numeral 9 refers generally to anantenna structure illustrating the use of the damping means of thisinvention on an antenna element secured at both ends.

As shown in FIGURE 1, antenna structure 8 may include a mast 11 and acrossbar or boom 12, which boom may be secured to mast 11 byconventional means, such as, for example, by clamp 14. In addition,antenna structure 8 may also include a plurality of antenna elements 16,which antenna elements may be cantilever mounted, as shown in FIGURE 1,by conventional fastening means, such as, for example, by clamp 18, ormay be an elongated rod or tube attached at its mid-point to thecrossbar. As is conventional, mast 11, boom 12, and elements 16 arepreferably tubular with elements 16 being of relatively small diameter.

As shown in FIGURE 2, antenna structure 9 may include a pair of masts 11having a pair of crossbars, or booms, 12 secured thereto conventionally,as by clamps 14, for example. In addition, a plurality of antennaelements 16 may be secured conventionally at their end portions 120between the crossbars, as shown in FIGURE 2, for example, by clamps 118.

The cantilever antenna elements 16, as shown in FIG- URE 1, may havesecured to their free ends 20 a damping device 22 to substantiallyeliminate vibration due to vibration producing forces, particularly windforces. As

' shown in FIGURE 2, damping device 22 may be secured inwardly of themounted ends 20 of antenna elements 16 for the same purpose.

As shown best in FIGURES 3 and 4, damping device 22 may be wheel-like inappearance and have a disc like portion, or Web, 25 connecting a hub 28and a rim 30. As shown in FIGURE 3, hub 28 and rim 30 extend axially inopposite directions, but it is to be appreciated that rim 30 is notmeant to be limited to the exact configuration shown. Web portion 25 ispreferably relatively thin and readily flexible and may be a rubbermembrane. Hub 28 may likewise be of rubber and may be integrally formedwith the web portion. Hub 28 is, of course, of a diameter so as toreadily receive the antenna element so that damping device 22 may besecured to the antenna element by any conventional means, such as, forexample, by a clamp (not shown) over hub portion 28.

Rim 30 must be of greater weight than is web portion 25, and, as isshown in FIGURE 3, may consist of a center layer, or ring 311, of rubber(which may be integrally formed with web portion 25) and an inner andouter heavier layer, preferably of metal, which may be rings 32 and 33,which rings may be secured to the inner and outer surfaces of the rubberring, respectively, in any conventional manner. It is to be appreciated,of course, that the needed weight could be provided in other waysobvious to one skilled in the art, such as, for example, by a relativelylarge rubber ring formed integrally with web 25 or attached to any onesurface of ring 31,

without departing from the teachings of this invention.

As shown in FIGURE 1, the damping device of this in vention ispreferably mounted near the free end of a oanti lever antenna element.When the antenna element is mounted at both ends, however, as shown inFIGURE 2, the damping means of this invention is secured to the antennaelement inwardly of the mounted ends. The exact positioning and sizeof'each damping device depends, of course, upon the particular antennaelement utilized. With respect to use of the antenna damping device onan antenna element secured at both ends, however, it has been found thatthe damping device operates very eifectively if placed one eighth of thedistance from each end of the antenna element. In practice, of course,the damping device 22 is placed on the antenna element and then adjustedas to position for the particular antenna element and damping deviceutilized until vibration issubstantially eliminated after which theantenna. structure is ready for use.

FIGURE illustrates the manner in which the damping device 22 absorbs theenergy imparted to the antenna element by vibratory .forces actingthereon. When the antenna element starts tovibrate, the damping deviceis also caused to vibrate, as shown by the dotted lines in FIGURE 5. Theflexible web portion 25 readily vibrates and due to the weight at thefree end of the web portion (which vibrates out of phase with theantenna element), substantially all vibration is quickly damped out ofthe antenna element.

From the foregoing, it should be evident to those skilled in the artthat the damping'device of this invention provides a means forsubstantially eliminating vibration in an antenna element and can beutilized regardless of the manner in which the antenna element ismounted.

What is claimed as my invention is:

1. In an antenna structure, the combination of: a substantially rigidantenna element a portion of which is subject to vibratory forces; and adamping member connected tothe portion of said antenna element subjectto vibratory forces, said damping member having'a readily flexibleportion extending outwardly from said antenna element and a secondportion of greater weight than said readily flexible portion with saidsecond. portion being connected to and extending from said readilyflexible por tion whereby the energy of vibrations transferred to saidantenna element from saidvibratory forces are absorbed by said dampingmember.

2. The combination of claim 1 wherein said readily.

5g. flexible portion is of rubber and said portion of greater Weightincludes metallic Weighting means.

3. The combination of claim 1 wherein said antenna element is securelyfastened at both ends and said portion subject to vibratory forces istherebetween, and said damping means is connected to said portionsubject to vibratory forces at a distance substantially one-eighth ofthe-distance from the end of said antenna element.

4. In an antenna structure, the combination of: a substantially rigidantenna element a portion of which is subject to vibratory forces; andannular damping means for absorbing energy transferred to said antennaelement by said vibratory forces, said damping means having asubstantially disc-shaped and readily flexible portion with a centralaperture through Which said antenna element is received and a secondportion of greater weight than said dis'c-shapedportion, said secondportion being connected to the periphery of said disc-shaped portion.

5. The combinatin of claim 4 wherein said disc-shaped portion is ofrubber and said second portion isan annular ring extended from theperiphery of said disc-shaped portion substantially coaxially with saidantenna element.

6. The combination of claim 5 wherein said annular ring includes acenter layer of rubber integrally formed with said second portion and anupper and lower layer of metal.

7. A damping device for substantially eliminating vibrations in anantenna element due to vibratory forces acting thereon, said dampingdevice comprising: a substantially disc-shaped portion of relativelythin, readily flexible material, said portion having a central aperturetherein of a size to receive an antenna element; a hub adapting saiddamping device for mounting on an antenna element received in saidcentral aperture; and a rim extending substantially normally from theperiphery of said discshaped portion, said rim being of greater weightthan said disc-shaped portion. 7

8.-The combination of claim 7 whereinsaid disc-like portion is of rubberandis integrally formed with said hub and at least a part of said rim.

References Cited by the Examiner FQREIGN PATENTS 1,152,309

2/57 France. 748,318 4/ 5 6 Great Britain. 842,060 7/60 Great Britain.

HERMAN KARL SAALBACH, Primary Examiner.

1. IN AN ANTENNA STRUCTURE, THE COMBINATION OF: A SUBSTANTIALLY RIGIDANTENNA ELEMENT A PORTION OF WHICH IS SUBJECT TO VIBRATORY FORCES; AND ADAMPING MEMBER CONNECTED TO THE PORTION OF SAID ANTENNA ELEMENT SUBJECTTO VIBRATORY FORCES, SAID DAMPING MEMBER HAVING A READILY FLEXIBLEPORTION EXTENDING OUTWARDLY FROM SAID ANTENNA ELEMENT AND A SECONDPORTION OF GREATER WEIGHT THAN SAID READILY FLEXIBLE PORTION WITH SAIDSECOND PORTION BEING CONNECTED TO AND EXTENDING FROM SAID READILYFLEXIBLE PORTION WHEREBY THE ENERGY OF VIBRATIONS TRANSFERRED TO SAIDANTENNA ELEMENT FROM SAID VIBRATORY FORCES ARE ABSORBED BY SAID DAMPINGMEMBER.